Code comparison for multiple kernels

A recent ACM paper, “A Tale of Four Kernels” compares FreeBSD, Linux, OpenSolaris, and the Windows Research Kernel in terms of code style and structure. The paper itself has a lot of blibber blabber, but it’s interesting to compare the code statistics between the different kernel types. I’d like to see a comparison between different BSD kernels; the gap between the Windows Research Kernel and Linux, for instance, is too great to be able to draw very concrete solutions. (via)